Ti-Ni SMA film actuated Si cantilever beams for MEMS probe card

We present a new MEMS probe card, which is composed of silicon (Si) cantilever beams actuated by titanium-nickel (Ti-Ni) shape memory alloy (SMA) films. Since Ti-Ni film can yield a higher work output per unit volume, the Ti-Ni film-actuated Si cantilever beam has the potential as a MEMS probe card to generate a large contact force between a probe and electrode pad. The cantilever beam produces a contact force by not only cantilever bending in contact but also the shape memory effect (SME) of Ti-Ni film arising from Joule´s heating. The SME of the Ti-Ni film containing Ti atom of 50.5% to 53.2% can generate an additional contact force of 200 μN on average on applying an electric power of 500 mW to the film. The Ti-Ni film-actuated Si cantilever beam could be a key element for a successful MEMS probe card with larger contact force and smaller size.